code-quality-principles

## Table of Contents

- [KISS (Keep It Simple, Stupid)](#kiss-keep-it-simple-stupid)
- [YAGNI (You Aren't Gonna Need It)](#yagni-you-arent-gonna-need-it)
- [SOLID Principles](#solid-principles)
- [Quick Reference](#quick-reference)
- [When Principles Conflict](#when-principles-conflict)
- [Integration with Code Review](#integration-with-code-review)

# Code Quality Principles

Guidance on KISS, YAGNI, and SOLID principles with language-specific examples.

## KISS (Keep It Simple, Stupid)

**Principle**: Avoid unnecessary complexity. Prefer obvious solutions over clever ones.

### Guidelines

| Prefer | Avoid |
|--------|-------|
| Simple conditionals | Complex regex for simple checks |
| Explicit code | Magic numbers/strings |
| Standard patterns | Clever shortcuts |
| Direct solutions | Over-abstracted layers |

### Python Example

```python
# Bad: Overly clever one-liner
users = [u for u in (db.get(id) for id in ids) if u and u.active and not u.banned]

# Good: Clear and readable
users = []
for user_id in ids:
    user = db.get(user_id)
    if user and user.active and not user.banned:
        users.append(user)
```

### Rust Example

```rust
// Bad: Unnecessary complexity
fn process(data: &[u8]) -> Result<Vec<u8>, Box<dyn std::error::Error>> {
    data.iter()
        .map(|&b| b.checked_add(1).ok_or("overflow"))
        .collect::<Result<Vec<_>, _>>()
        .map_err(|e| e.into())
}

// Good: Simple and clear
fn process(data: &[u8]) -> Result<Vec<u8>, &'static str> {
    let mut result = Vec::with_capacity(data.len());
    for &byte in data {
        result.push(byte.checked_add(1).ok_or("overflow")?);
    }
    Ok(result)
}
```

## YAGNI (You Aren't Gonna Need It)

**Principle**: Don't implement features until they are actually needed.

### Guidelines

| Do | Don't |
|----|-------|
| Solve current problem | Build for hypothetical futures |
| Add when 3rd use case appears | Create abstractions for 1 use case |
| Delete dead code | Keep "just in case" code |
| Min